Almost half of all Cobb homeowners saw the gross assessed value of their houses reduced this year, and four of five county commissioners were among them.

County assessors lowered values on 107,773 of Cobb’s 230,437 residential properties this year, or 47 percent.

That’s more than in 2011, when about 41 percent of Cobb homeowners saw their assessments go down, but far fewer than in 2010, when nearly 60 percent declined.

In 2009, assessors lowered values on just 7 percent of Cobb homes.

Among the five county commissioners, only JoAnn Birrell, of northeast Cobb, who joined the commission in 2010, did not have a lowered house assessment this year.

But the assessment on Commissioner Woody Thompson’s Mableton home has plummeted three times in recent years.

In 2007, his brick ranch home on Austin Drive was assessed at $145,090, according to public tax records. This year, it was assessed at just $36,420 — a drop of nearly 75 percent, or $108,670.

“We were going to move, but now we’re stuck,” Thompson said. “The house isn’t worth anything.”

Thompson said he moved into the home in 2005 to assist his aging mother. After she died in 2007, he took over ownership and sold his home off Austell Road.

He didn’t foresee the economic downturn that led to a rash of foreclosures, particularly in south Cobb.

“I wish I would have known. I would have sold the house,” Thompson said. “But nobody knew what was going to happen with the economy.”

Although none of the other commissioners have taken the hit Thompson has, they have all seen their home assessments lowered in recent years.

Bob Ott, who represents southeast Cobb and joined the commission in 2008, has seen his house assessment lowered twice since 2007. That year, his home on Pebble Creek Road, in the Wheeler High School attendance zone, was assessed at $383,880. This year, it was assessed at $257,440 — a drop of 33 percent, or more than $126,000.

Ott said he paid $179,000 for the Terrell Mill Estates house in 1994, and has added on to it. Although he’s not planning on moving, he doesn’t believe assessed values always match the market.

“That is what it is assessed at. It is not necessarily what it is going to sell for,” he said.

Chairman Tim Lee’s home assessment had held steady amid the economic downtown until this year. In 2011, his home on Bentcreek Drive, near Scufflegrit Road, was assessed at $238,510. This year, the assessment was $209,550 — a decline of 12 percent, or $28,960.

Lee’s home is in the Sprayberry High School zone.

Northeast Cobb Commissioner JoAnn Birrell is the only one of the five whose home assessment did not change this year, though it did drop in 2010. She lives on Nottoway Trail, which is also in the Sprayberry High zone.

In 2007, her house was assessed at $292,810. Since 2010, it has been assessed at $251,070 — a drop of 14 percent, or $41,740.

Helen Goreham, who lives in and represents northwest Cobb, has seen the least loss in assessed value on her home. She lives on West Hampton Drive, near where Burnt Hickory meets Due West Road.

From at least 2007 and through 2011, her house was assessed at $226,280. This year, the assessed value is $213,020 — a decline of about 6 percent, or $13,260.

In Mableton, Commissioner Thompson said he is frustrated that his home value is impacted by unkempt and foreclosed properties within and around his 50-year-old neighborhood. A real estate broker himself for nearly 40 years, Thompson said he is seeing some homes back at 1970s values.

But besides being a market-rate factor, assessors are required to figure such data in their property assessments, said Phil Hogsed, Cobb’s chief tax assessor.

“Georgia law now requires tax assessors to use distressed sales along with traditional arm’s-length sales in determining property values,” he said. “Some areas are impacted more by this than others.”

Economist Roger Tutterow said southwest Cobb has struggled to retain values in part because it lacks the transportation connectivity other parts of the county and region have, and the schools are not as high achieving as in other areas of the county.

That makes any area less desirable for homebuyers, he said, and further drives values down.

For Thompson, though, not all is negative. He said he is thankful that his house is paid for, and his property taxes are low because he qualifies for the senior school tax exemption. His house is in the Pebblebrook High School zone.

As for challenging an assessed value, Hogsed said about 2,600 homeowners have appealed their 2012 assessments. Monday is the deadline for most Cobb homeowners to file an appeal, though it’s too early to say how many of those who have already appealed have succeeded, he said.

“Generally, most appellants want a lower value,” Hogsed said.

As for the commissioners’ assessments, there is no indication any of the five improperly tried to influence his or her assessment.

Still, do assessors know when they are assessing a home owned by a county commissioner or other prominent person?

“Common sense would suggest that a seasoned appraiser probably does know, as they work assigned areas of the county,” Hogsed said.